Radio vacuum-tube construction



April 16, 1929.

c. E. FITCH RADIO VACUUM TUBE CONSTRUCTION Filed May 6, 71926 Patented Apr. 16, 1929.

UNITED STATES 1,709,393 PATENT OFFICE.

CLAUDE E. FITCH, OF WILMETTE, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

RAYTHEON MANUFACTURING COMPANY, OF

PORATION OF DELAWARE.

CAMBRIDGE, MASSACHUSETTS, A COR.-

RADIO VACUUM-TUBE CONSTRUCTION.

Application filed May 6, 1926. Serial- No. 107,131.

The purpose of this invention is to provide an improved form and character of contact terminal of radio vacuum tube, and an improved method of ensuring the conductive junction between the inleading wires and the terminal pins by which the circuit contacts of the tube are made when it is mounted in the socket, or other circuit-connecting support. It consists in the elements and features of construction and method shown and described, as indicated in the claims.

In the drawings Figure 1 is an elevation of a radio vacuum tube of familiar form and construction, but

having the terminal contact pins constructed Figure 5 is a section at the line 5-5- on Figure 1-.

Figure 6 is a bottom plan view of the tube. In the drawings, A represents the base of the vacuum tube, made usually of hard rubber, bakelite or the like, having .the metal tubular terminal pins,- B, made rigid with the 5 end of the base in any suitable manner for having the inleading wires, C, pass through the axial cavities of the pins, B, respectively, from within the cavity of the base before the base is joined to the bulb.

The customary means and method of effecting sure conductive junction between the inleading wire and the terminal contact pin through which the wire extends as above described, is to solder the wire to the pin at the end of the latter, that is, at the emergence of the wire from the end of the axial cavity of the pin. This method has been found objectionable because of the difficulty of obtaining perfect uniformity in the to size and protrusion of the little lumps of solder technically called beads which become deposited at and protrudin from the ends of the several pins. (usually ourg and in instances in which a. larger lump is ormed wire therein, to sto on the one pin than on the others, it is liable to occur that the other pins having less protruding lumps ivill fail to make contact with their respective co-operating contacts in the socket, because the more protruding terminal solder lump of the first pin holds the others out of contact. And in other instances in which the socket for the tube has individual small sockets for the several pins, a solder lump on any one of the pins protruding a trifle laterally beyond the diameter of the pin, prevents that pin from entering its socket and so keeps the other pins out of circuit-closing position.

These difliculties and defects are overcome and avoided in the present invention by providing a slender securing pin, D, commonly called an escutcheon pin diametered for fitting tightly in the axial cavity of'the tubular contact pin when the inleading wire is also therein, said securing pin havinga rounded head adapted, when the securing pin is forced into the axial cavity of the tubular contact pin alon side the circuit on the ends of the tubular pinand on t e out-turned end portion of the wire, and pinch and flatten the wire securely against the inner wall of' the axial cavity of the tubular pin, and also pinch the out-bent end portion of the wire againstthe end of the tubular pin as seen in Figure v4, wherein there is shown at the right end of the two tubular pins, seen in that figure, the protruding portion, 0, of the inleadin wire as it may be seen protruding for a su stantial distance while the secur ing pin is being forced in, said protruding portion of the wire being bent aside toform a. hook engaging the end of the tubular pin, so that the wire will not be liable to be drawn in by the friction of the securing pin in forcin the latter member. At the left hand of t e two tubular contacts shown in this figure, the inleading wire is shown as it appears when the process of securing it is finished, the excess protruding ortion of the wire having been clipped 0 close to the head of the securing plIlS.

Beside the advantages incidentally indicated above, the method described consist-.

ing in securing the inlcading wires in the tubular inleads by pin instead of soldering at the ends, has the following advantages:

(1) Avoidance of the soft metal (solder)v for'maki'ng the contact and ,substituting a metal not so liable to be abraded by unnecessary force which is liable to be used in thrusting the tube into socket, or to become oxidized introducin greater electrical resistance, or to be fused as will occur in case of imperfect contact, which imperfect contact is particularly likely to; be caused by the jamming and flattening or abrading of the solder terminal of one or more of the contact pins which are thereby held out of contact by the others which are not re-- duced in length.

(2) Avoidance of the formation of a thermo-electric couple which is involved in the use of the soft metal (solder) in junction with the brass or bronze, which tends to generation of electric current which, particularly in the case of a tube having filament energized by alternating current, interferes very seriously with the efficiency of the tube for receiving, the pulsations of the current generated through the thermo-clecescutcheon pin, beside metallic contact pin protruding therefrom for making circuit-closing contact; inlcading circuit wires, extending through the base and out through the tubular contact. pin, and a headed pin which is fitted tightly in the axial cavity of the tubular pin alongside of the clamps the wire extending therein throughout said extent and having its head extending over the end of thetuhular pin; whereby such headed clamping pin forced into the tubular contact pin until the head is stopped on the end of the. latter, serves for clamping the inleading wire. into contact with the tubular pin, and by its head afi'ords suitable contact terminal for the tubular pin.

2. A vacuum tube base having a tubular metallic contact pin protruding therefrom for making circuit-closing contact; an inlcading circuit wire extending; through the. base and outthrough the tubular contact pin and folded outwardly across the thickness of the tube base, and a headed clamping pin which is fitted tightly in the axial cavity of the tubular pin alongside the wire therein, with its head extending over the end of the tubular pin and bein stopped thereby with the out-folded end of the wire pinched between said head and the end of the tube.

In testimony whereof, I have hereunto set my hand at Chicago, Illinois, this 3d.day of May, 1926.

CLAUDE E. FITCH.

CERTIFICATE or CORRECTION.

Patent No. 1,709, 393.

Granted April 16, 1929, m

CLAUDE E. FITCH.

It is hereby certified that error appears in theprinted specification of the above numbered patent requiring correction as follows:

Page 2, line 42, claim I, torthe article "the" first occurrence, read "mari; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signedjand sealed this 28th day of May, A. D. 1929.

(Seal) M. J. Moore, Acting Commissioner of Patents.

GERTIi iCATE OF CORRECTION.

Patent No. l,709,393. I Granted April 16, 1929, to

CLAUDE E. FITCH.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, line 42, claim 1, for the article "the" first occurrence, read "and"; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the ease in the Patent Office.

Signed and sealed this 28th day of May, A. D. 1929.

M. J. Moore, (Seal) Acting Commissioner of Patents. 

